login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Numbers m with result 1 under iterations of {r mod (max prime p <= r)} starting at r = m.
1

%I #23 Aug 04 2018 06:39:29

%S 1,4,6,8,12,14,18,20,24,27,30,32,35,38,42,44,48,51,54,57,60,62,65,68,

%T 72,74,77,80,84,87,90,93,95,98,102,104,108,110,114,117,119,121,125,

%U 128,132,135,138,140,143,145,147,150,152,155,158,161,164,168,171

%N Numbers m with result 1 under iterations of {r mod (max prime p <= r)} starting at r = m.

%C Terms are composites for all n >= 2.

%C Complement of A175089. [_Jaroslav Krizek_, Feb 05 2010]

%C Numbers m such that A121559(m) = 1. - _Michel Marcus_, Aug 22 2014

%e Iteration procedure for a(6) = 14: 14 mod 13 = 1.

%e Iteration procedure for a(10) = 27: 27 mod 23 = 4, 4 mod 3 = 1.

%t (x /. Solve[Fold[Mod[#1, #2] &, x, Reverse[Prime /@ Range[40]]] == 1,

%t x, Integers]) /. C[1] -> 0 (* _Morgan L. Owens_, Jun 22 2016 *)

%Y Cf. A007917 and A064722 (both for the iterations).

%K nonn

%O 1,2

%A _Jaroslav Krizek_, Jan 28 2010

%E More terms from _Michel Marcus_, Aug 22 2014